CAPTCHA/Captcha (Completely Automated Public Turing Test to Tell Computers and Humans Apart) is a technique for challenge-response tests used in computing environment. CAPTCHAs can be deployed to protect systems vulnerable to e-mail spam and automated postings, by running a challenge-response test on the systems, for example, a user's computer or smart phone. CAPTCHA can also be used to prevent or at least make it harder for machines to automatically download files.
The process usually involves a server asking a user to complete a test which the server is able to generate and send to the user's user equipment and then, upon a reply from the user equipment, determine whether the user has inserted the right answer to the test. The test is supposed to be easy to solve for a human but not a computer. Because computers are supposed to be unable to solve the CAPTCHA, any correct solution received by the server is presumed to be originating from a human, thus distinguishing humans from computers. A common type of CAPTCHA requires that the user types in letters and/or digits displayed in a distorted image that appears on a screen before e.g. registration, downloading and login to provide a secure environment for the application service providers.
It is also known that the evolution of CAPTCHAs has led to a form of advertising/advertisement (often abbreviated as “Ad”). In essence, the core concepts and purpose of CAPTCHAs will remain unchanged. Instead of seeing a distorted image that contains generated characters, an image or video containing advertisements may be displayed.
In video-based CAPTCHA solutions, a CAPTCHA text is embedded into 5˜10 seconds flash video. Users need to identify the floating CAPTCHA text in the video and input the text. A company named NuCaptcha provides this CAPTCHA solution, as can be seen via http://www.nucaptcha.com, retrieved on Feb. 23, 2011. However, there is a problem that users immediately may recognize and remember the CAPTCHA characters in the Ad video without having to and/or wanting to see the whole Ad video. Although he/she has to submit CAPTCHA answer after the video has ended, users may not like to wait for 5˜10 seconds, so they may choose to skip the video by scanning other webs. Thus, the purpose of advertising will not be achieved effectively. Moreover, many user equipments cannot show videos of certain formats, e.g. flash video, simply because they lack a compatible decoder. Users of such user equipments would not be able to solve the CAPTCHA, since they could not even see the video.
Another kind of CAPTCHA advertising is based on image. In this solution, the CAPTCHA text is some words comprised in an Ad picture. These solutions usually either do not force the user to type in advertisement words or contains only advertisement without randomly generated and distorted characters. The former may make users have the chance to ignore advertisement, and the latter may be easier hacked by some Optical Character Recognition (OCR) and image recognition technologies.
Therefore, a CAPTCHA method and system with improved advertising effect and security is needed.